1. Field of the Invention
The present invention relates to a method of fabricating a semiconductor device.
2. Description of the Related Art
There is a semiconductor device (IC chip) mounting scheme called a TAB (Tape Automated Bonding) system by which a semiconductor device is mounted on a TAB tape. In this case, bump electrodes provided on a semiconductor device are connected to finger leads (inner leads) on the TAB tape by gold-tin eutectic bonding, gold-gold thermo-compression bonding or the like.
Semiconductor devices are generally designed in such a form that connection electrodes formed on a silicon wafer (semiconductor device body or die chip) are exposed through an opening formed in a passivation film formed on the silicon wafer. Bump electrodes (projection electrodes) are formed on the connection electrodes. The connection electrodes are made of a base metal such as aluminum or aluminum alloy. In fabricating a semiconductor device with such a structure, an insulative natural oxide layer formed on the surface of each connection electrode is removed with argon ions by dry etching before a bump electrode is formed on the connection electrode.
To better protect the surface of a semiconductor device, the structure, in which a protective film made of polyimide is formed on the passivation film made of silicon nitride or the like, is proposed. In fabricating a semiconductor device with this structure, dry etching with argon ions is carried out to remove the natural oxide layer formed on the surface of the connection electrode, after the protective film made of polyimide is formed. The surface layer of the protective film is altered and deteriorated by the argon ions. This decreases the insulating resistance to result in inadequate insulation, so that electric leakage or short-circuiting may at last occur between the adjoining connection electrodes.